This invention relates to a method for reconnecting partitioned ports in a network. Specifically, the invention relates to a method for reconnecting partitioned ports of a repeater that is part of a network constructed with twisted pair wiring.
Repeaters conforming to IEEE 802.3 Standard, hereby expressly incorporated by reference for all purposes, partition ports that have excessive collision activity. The IEEE 802.3 Standard defines a collision as simultaneous receive and transmits activity at a single port. The IEEE 802.3 Standard also defines a port with excessive collision activity as a port that participates in each collision of a preceding set of 32 consecutive collisions. Excessive collision activity also includes a prolonged collision for a particular port.
A partition state machine partitions ports which have excessive collision activity. A partitioned port can receive transmissions, but the repeater does not relay any incoming data packets from partitioned ports. The partition state machine continues monitoring partitioned ports to determine whether it should reconnect these ports.
The IEEE 802.3 Standard defines a partitioning/reconnection algorithm which requires reconnection of a partitioned port upon collision-free transmissions or receptions relative to the port lasting a predefined minimum period. A term "port activity" defines transmission or reception at a port. Thus, the standard algorithm reconnects a partitioned port upon collision-free port activity. The IEEE 802.3 Standard sets the minimum period at or about 512 bit times.
This partitioning/reconnection algorithm may cause problems when used with repeaters that are part of a network conforming to the IEEE 10 BASE-T Standard. The 10 BASE-T Draft 10 Standard implements a network by use of twisted pair wiring, and is expressly incorporated by reference for all purposes. Networks carried out with twisted pair wiring are susceptible to installation difficulties resulting in network performance degradation due to use of inappropriate cabling. A particular port's transmit wires may not be properly terminated or the network may use untwisted wiring. In either case, transmissions from that port can produce cross-talk on the associated receive wiring of the port, thereby creating a collision. The repeater thereafter detects a collision every time the repeater tries to transmit to a node connected to such a port. The partitioning system properly partitions such a port. Unfortunately, the IEEE 802.3 Standard reconnection algorithm reconnects upon a partitioned port a minimum time duration collision-free reception at the port. The wiring problem on the transmission side of the port does not affect the reception. In this case, the partition state machine will reconnect the partitioned port after each partition, allowing later transmissions to cause collisions. This cycle degrades the performance of the network.